1. Field of the Invention
The present invention relates to a display apparatus and a method for controlling the display apparatus.
2. Description of the Related Art
A high definition medical monitor (display apparatus for displaying medical images) generally displays medical images which are output from such an external apparatus as a PC (Personal Computer). However in future it is expected that the functions of medical monitors will be more advanced, and medical monitors, which can easily display medical images on medical monitors alone, will be developed. And as such medical monitors, the development of portable monitors (display apparatuses) is expected. If this type of medical monitor is used, the images can be read using a high functioning PC (software stored on PC) and monitor, and explanations to patients, for example, can be performed using the monitor alone (simply displaying the medical images on the monitor alone). It is also expected that such a medical monitor will be connected to a network for displaying images. Furthermore it is expected that the calibration schedule setting and calibration execution instructions via a network, now performed on a PC, will be performed on the monitor.
In the case of the above mentioned monitor, the view of displayed images (display characteristics) must conform to a target value. However an image that is input from a PC (hereafter “external input image”) may change depending on the characteristics of the graphic board provided in the PC or the processing performed in the PC (e.g. image processing executed in the PC). In other words, the display characteristics of an external input image and those of an image displayed by a monitor alone (single unit display image) may differ even if a same image is displayed. Therefore as the display characteristic calibration, the display characteristic calibration of the external input image (hereafter “link calibration”) and the display characteristic calibration of the single unit display image (hereafter “single unit calibration”) must be performed.
A prior art on the calibration is disclosed in Japanese Patent Application Laid-Open No. 2002-057911 and Japanese Patent Application Laid-Open No. 2005-208548. In concrete terms, Japanese Patent Application Laid-Open No. 2002-057911 discloses a technique to correct the result of software-based calibration according to the result of the device calibration. Software-based calibration is performed using the data acquired by reading the printed result of a printer using a scanner. Device calibration is automatically performed in the printer based on the potential of a latent image formed on a photosensitive drum and the density of a toner image.
Japanese Patent Application Laid-Open No. 2005-208548 discloses a technique to perform photometry using a photometric unit disposed to face a liquid crystal display unit, and perform calibration based on the difference value between the result of the photometry and a predetermined ideal value.
According to a guideline for the quality control of medical monitors, it is demanded that a constancy test be performed on a monitor periodically, and calibration is performed if the test result indicates failure (if the constancy of the display characteristics of a monitor is diminished). Therefore software for automatically calibrating a medical monitor according to a predetermined schedule, and software for executing calibration of a medical monitor via a network are sold in the marketplace.